Free wheel device

ABSTRACT

A free wheel unit including a drive unit with an outer surface forming an inner race and having an annular groove in the axial center thereof in which is disposed an expandable split bearing ring, a driven unit or outer race provided with a plurality of circumferentially arranged ramped recesses in each of which is disposed a roller, the rollers being biased radially outward into engagement with the ramped recesses by the expandable split bearing ring, the split bearing ring providing friction contact to rotate the rollers down the ramped recesses into engagement with the inner race to effectively lock the driven unit to the drive unit when the latter is rotated in one direction and to rotate the rollers out of engagement with the inner race when the drive unit is rotated in the opposite direction to place the driven unit in a free wheeling condition relative to the inner drive unit.

United States Patent 1191 McEwen [54] FREE WHEEL DEVICE [75] Inventor:John C. McEwen, Indianapolis, Ind.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Aug. 27, 1971 [21] Appl. No.: 175,569

[52] US. Cl ..192/45 [51] Int. Cl. ..F16d 15/00, Fl6d 41/06 [58] Fieldof Search ..l92/27, 38, 44, 45;

[56] References Cited UNITED STATES PATENTS 3,103,998 9/1963 Watson..l92/45 3,087,589 4/1963 Gorsky ..192/45 1,942,909 l/l934 VonThungen.... ...l92/45 2,481,066 9/1949 Bagge ...l92/45 3,054,489 9/1962Fahlberg ..l92/45 FOREIGN PATENTS OR APPLICATIONS 918,339 10/1946 France..192/45 1,154,767 11/1957 France ..192/45 Primary Examiner-Allan D.Herrmann A ttorney .I. L. Carpenter & Arthur N. Krein 57 ABSTRACT A freewheel unit including a drive unit with an outer surface forming an innerrace and having an annular groove in the axial center thereof in whichis disposed an expandable split bearing ring, a driven unit or outerrace provided with a plurality of circumferentially arranged rampedrecesses in each of which is disposed a roller, the rollers being biasedradially outward into engagement with the ramped recesses by theexpandable split bearing ring, the split bearing ring providing frictioncontact to rotate the rollers down the ramped recesses into engagementwith the inner race to effectively lock the driven unit to the driveunit when the latter is rotated in one direction and to rotate therollers out of engagement with the inner race when the drive unit isrotated in the opposite direction to place the driven unit in a freewheeling condition relative to the inner drive unit.

4 Claims, 3 Drawing Figures EE WHEEL\\\ PATENTEU MAY 1 51973 ATTORNEYFREE WHEEL DEVICE This invention relates to a free wheel unit and, inparticular, to an overrunning roller clutch device.

Various forms of free wheel devices are known in the art. Some of thesefree wheel devices are known as cage types in which a cage carries ballor roller bearings between an outer race housing and an inner racehousing having portions of wedge-shaped configuration and for effectingradial movement of the balls or rollers into and out of engagement withthe races. Another type of free wheel device, which may be referred toas a cageless type device, is disclosed in U.S. Pat. No. 3,103,998issued Sept. 17, 1963, to Kenneth Watson.

In all of the prior known free wheel devices, the ball or rollers arelocked against rotation when they are in a position to engage the drivemember of the device to the driven member while being free to rotatewhen in position to effect overriding or free wheeling of the drivendevice relative to the drive unit. Accordingly, in all of the priorkriown free wheel devices, the balls or rollers, since they slip or slidein rubbing fashion during rotation while free wheeling, are subjected togalling or the creation of roller flats thereon. This, of course, limitsthe operational life of the unit and the speed at which they can beoperated.

Accordingly, it is an object of this invention to provide an improvedfree wheel unit of simple construction which may be used at highoperating speeds without having the rollers thereof in rolling contactwith either the inner raceway or the outer raceway with which theycooperate when the device is free wheeling.

It is a further object of this invention to provide an improved freewheel unit in which the rollers of the unit do not rotate when the unitis in a free wheel condition to thereby reduce rubbing and subsequentwear between the roller elements and the raceways with which theycooperate.

These and other objects of the invention are attained by means of a freewheel unit having a bronze split bearing ring mounted in a centralgroove in the inner cylindrical race of a drive unit, a driven unithaving an inner diameter bored surface with a plurality ofcircumferentially arranged outer raceway recesses therein providinginclined ramp surfaces encircling the drive unit and a roller positionedin each of the recesses and biased radially outward by the split bearingring. When the drive unit is rotated in an engaged direction, the splitring which rotates in the same direction relative to the inner driveunit causes the rollers to rotate on the ramp surface to a position inwhich they are wedged between the inner cylindrical race and the outerrace ramp surfaces to in effect engage the inner drive unit with thedriven unit. In the overrunning direction, the split ring expands andspaces the rollers from the cylindrical inner race so that they are outof driving engagement with the inner drive unit, relative motionoccurring between the split ring and the inner race, the split ringbeing in sliding engagement in the full overrunning position with therollers whereby the rollers do not rotate.

For a better understanding of the invention, as well as other objectsand further features thereof, reference is had to the following detaileddescription of the invention to be read in connection with theaccompanying drawings, wherein:

FIG. 1 is an end view of a free wheel unit of the invention;

FIG. 2 is a sectional view of the free wheel unit of the invention takenalong line 2-2 of FIG. 1; and,

FIG. 3 is a view similar to FIG. 1 of an alternate embodiment of thefree wheel unit of the invention.

Referring now to FIGS. 1 and 2, there is shown a simplified version of afree wheel unit constructed in accordance with the principles of theinvention which includes a drive member, generally designated 10, havinga drive shaft portion 12 and an enlarged annular journal portion 14 withan annular groove 16 axially centrally thereof to receive a splitbearing ring 18 therein, the ring being made of bronze or other suitablebearing material. The width of the split ring relative to the groove issuch so that the split ring, when in frictional contact with the drivemember and with other elements of the free wheel unit as describedhereinafter, will rotate with the drive member but relative thereto. Thedrive member 10, made of steel, has the outer surface of the journalportion thereof case hardened to provide an inner raceway or race 20.

Encircling the inner drive member 10 is a driven member 22 in the formof a cup-shaped case hardened steel shell provided with a bore 24 of adiameter slightly larger than the diameter of the inner race 20 of drivemember 10, which terminates at a radially inward extending shoulder 26.A plurality of circumferentially arranged outer raceway recesses areprovided in the inner periphery of the driven member, four such recessesbeing provided in the embodiment of the free wheel unit shown. As seenin FIG. 1, each such recess is formed by spaced apart, radially outwardextending walls 28 and 32 with an annular inclined cam or ramp surface34 therebetween, the ramps extending in a circumferential direction.

A roller 36 is disposed at each of the recesses, with each roller beingnormally biased radially outward into frictional engagement with theinclined ramp surface 34 by means of the split ring 18 which engages theouter peripheral surface of the rollers longitudinally in the centerthereof. The rollers 36 are shown in FIGs. 1 and 2 in their freewheeling position, a position in which the drive member is rotated in acounterclockwise direction as seen in FIG. 1 with the driven member heldstationary and the rollers out of engagement with journal portion 14.

In operation, it will be seen from FIG. 1 that if the drive member 10 isrotated in a clockwise direction as seen in this figure, the split ring18 which is always in engagement with the rollers 36 will rotate due tofrictional engagement with the drive member in the same direction butrelative thereto and effect rotation of the rollers 36. This will causethe rollers 36 to roll down the inclined ramp surfaces 34 to moveinwardly, against the biasing action of the split ring 18, until theycome into tight binding engagement between the ramp surface 34 and theinner race 20. When this occurs, the driven member is then locked bymeans of this camming wedge efiect of the rollers 36 against the innerrace of the drive member. The drive member and driven member can now besaid to be in an engaged or drive position relative to each other.

When this clockwise rotation of the drive member 10 is terminated andthen the drive member is rotated in a counterclockwise direction as seenin FIG. 1, and the driven unit is held against rotation as by frictionalengagement with other elements not shown, the rollers 36 will be rotatedmomentarily by frictional engagement with the inner race 20 and, thenfurther rotation of the rollers 36 is effected by engagement of thesplit ring 18 therewith, the split ring now rotating in acounterclockwise direction with the drive member, but relative thereto,to cause each of the rollers to roll up the inclined ramp surfaces 34until they engage the wall 32 at which time they will be positionedradially outward from the inner race 20 of the drive member with an airspace therebetween. Each roller 36 when in this position is infrictional contact with its cooperating end wall 32 and ramp surface 34and, is thereby frictionally held against further rotation even thoughthe split ring 18 continues to rotate with the drive member 10, butrelative thereto. As the split ring 18 rotates with the drive member butrelative thereto, it slips relative to the rollers 36 when they are inthis free wheel state or position. Since the rollers do not rotate whenthe unit is in the free wheeling position, they are not subject togalling or having flats formed thereon and the unit is thus operationalat high speeds.

Thus, the only frictional driven engagement between the drive member 10and these rollers 36, when the unit is in a disengaged or free wheelposition, is through slip engagement of the bronze split ring 18 withthe drive member 10 and its sliding engagement with the central portionof the rollers. Thus, the rolling contact surface of each roller, whichis engageable with the journal portion 14 when engaged, is neversubjected to frictional rolling engagement with either the journalportion 14 of the drive member 10 or the ramp surfaces 34 of the outerraceway recesses when the device is free wheeling.

In the alternate embodiment of the free wheel unit of the inventionshown in FIG. 3, wherein like reference numerals indicate like parts,this unit is identical to that shown and described with reference toFIGS. 1 and 2 except for the provision of a tickler spring 38 positionedin each of the recesses in the driven member. Each spring 38 abuts atone end against the wall 32 of the recess and at its other end againstthe roller 36 to normally bias the roller in direction to travel downthe inclined ramp surface 34 to facilitate movement of the rollersinwardly against the biasing action of the split ring 18 into tightbinding engagement between the ramp surface 34 and the journal portion14 of the drive member 10 when the latter is rotated clockwise, as shownin FIG. 3.

When the drive member 10 is rotated counterclockwise, with the drivenmember 22 held against rotation, the rollers 36 as previously describedwill through frictional engagement against the split ring 18 be rotatedto roll up the inclined ramp surfaces 34 against the biasing action ofsprings 38 until frictional engagement of the rollers 36 against springs38 and ramp surfaces 34 prevents the rollers from spinning while thesplit ring then slips relative to the rollers which are then in the freewheel position out of direct engagement with the 5 journal portion ofthe drive member 10.

What is claimed is:

1. A free wheel device including a drive unit with an outer surfaceforming an inner race and having an annular groove centrally disposedtherein, an expandable split bearing ring positioned in said groove forrotation with said drive unit but relative thereto, a shouldered drivenunit encircling said drive unit, said driven unit having a plurality ofrecesses therein arranged circumferentially around said inner race, eachsaid recess being formed by spaced apart radially extending walls withan angular inclined ramp surface therebetween, a roller positioned ineach of said ramped recesses in engagement with said split bearing ringand biased thereby into engagement with said ramp surface of the recessin which it is positioned.

2. A free wheel device according to claim 1 further including a springpositioned in each of said recesses in position to bias said rollers ina direction down the inclined ramp surfaces of said recesses.

3. A free wheel device including a drive unit with an outer surfaceforming an inner race and having an annular groove centrally disposedtherein, an expandable split bearing ring positioned in said groove, ashouldered driven unit encircling said drive unit, said driven unithaving a plurality of ramped recesses therein arranged circumferentiallyaround said inner race, each said ramped recess being formed by spacedapart radially extending walls with an angular inclined ramp surfacetherebetween, a roller positioned in each of said ramped recesses inengagement with said split bearing ring and biased thereby intoengagement with said ramp surface of the ramped recess in which it ispositioned, said ramp surface of each of said ramped recesses beingspaced from said inner race of said drive unit such that when saidrollers are at one end of said ramped recesses said rollers are out ofengagement with said inner race and when said rollers are at theopposite end of said ramped recesses said rollers engage said inner raceto effect a driving connection between said drive unit and saidshouldered driven unit.

4. A free wheel device according to claim 1 further including a springpositioned in each of said ramped recesses in position to bias saidrollers in a direction down the ramp surfaces of said ramped recesseswhereby said rollers move radially inward into driving engagementbetween said outer surface of said drive unit and said shouldered drivenunit.

1. A free wheel device including a drive unit with an outer surfaceforming an inner race and having an annular groove centrally disposedtherein, an expandable split bearing ring positioned in said groove forrotation with said drive unit but relative thereto, a shouldered drivenunit encircling said drive unit, said driven unit having a plurality ofrecesses therein arranged circumferentially around said inner race, eachsaid recesS being formed by spaced apart radially extending walls withan angular inclined ramp surface therebetween, a roller positioned ineach of said ramped recesses in engagement with said split bearing ringand biased thereby into engagement with said ramp surface of the recessin which it is positioned.
 2. A free wheel device according to claim 1further including a spring positioned in each of said recesses inposition to bias said rollers in a direction down the inclined rampsurfaces of said recesses.
 3. A free wheel device including a drive unitwith an outer surface forming an inner race and having an annular groovecentrally disposed therein, an expandable split bearing ring positionedin said groove, a shouldered driven unit encircling said drive unit,said driven unit having a plurality of ramped recesses therein arrangedcircumferentially around said inner race, each said ramped recess beingformed by spaced apart radially extending walls with an angular inclinedramp surface therebetween, a roller positioned in each of said rampedrecesses in engagement with said split bearing ring and biased therebyinto engagement with said ramp surface of the ramped recess in which itis positioned, said ramp surface of each of said ramped recesses beingspaced from said inner race of said drive unit such that when saidrollers are at one end of said ramped recesses said rollers are out ofengagement with said inner race and when said rollers are at theopposite end of said ramped recesses said rollers engage said inner raceto effect a driving connection between said drive unit and saidshouldered driven unit.
 4. A free wheel device according to claim 1further including a spring positioned in each of said ramped recesses inposition to bias said rollers in a direction down the ramp surfaces ofsaid ramped recesses whereby said rollers move radially inward intodriving engagement between said outer surface of said drive unit andsaid shouldered driven unit.